1. Field of the Invention
The present invention relates to a positive resist composition which comprises a quinone diazide compound, an alkali-soluble resin and a specific solvent.
1. Description of the Related Art
A composition containing a compound having a quinone diazide group (a quinone diazide compound) and an alkali-soluble resin finds use as a positive resist in the production of integrated circuits.
Recently, with integrated circuits, miniaturization has proceeded with a rise in the integration level, which results in demands for formation of patterns of submicron order. To form such minute patterns with good reproducibility, it is essential that a uniform resist coating is formed and the resist composition has a larger depth of focus.
Hitherto, for the preparation of the resist composition, a cellosolve type solvent has been used as a solvent. In view of health problems of human beings, some solvents such as propylene glycol monomethyl ether acetate, cyclohexanone and ethyl lactate are proposed as substitutes for the cellosolve type solvent. However, the use of propylene glycol monomethyl ether acetate or cyclohexanone will decrease heat resistance of the resist. The use of ethyl lactate having a high viscosity will increase striations or cause some problem in coating such that an edge of a wafer is not coated.